Bandsaw spring tensioner
The adjuster supplied with the bandsaw is just a hand grip on the end of the tensioner bar as shown here. In order to change the tension significantly it is necessary to make many turns of the bar. If a short cranked handle were provided the adjustment would be much quicker and easier.
The tensioner bar runs in a very crude bent steel bracket. This scores the bar badly and the crome plated has been completely removed in places. At the other end of the adjuster bar is a hook that accepts the end of the tension spring. The hook is threaded M6 and turning the adjuster bar lengthens or shortens the protrusion of the hook and hence adjust the spring tension. The problem with this is that the threaded part of the hook is fairly short, circa. 50 mm, and this does not allow much variation in tension. |
These problems have been addressed. The header photo shows a small cranked handle has been added at the end of the adjuster bar. This was turned from a length of 25 mm round steel. This was turned down for a length of 18 mm so that it fitted in the adjuster tube. The piece was parted off 27 mm from the end and then cross drilled 6 mm for the bent steel handle. The shoulder was then fixed in the tube using epoxy resin and the handle secured with the same adhesive.
Also in the header photo can be seen a new bracket to support the adjuster bar. This is a steel bracket faced with 10 mm thick polyethylene (a bit of kitchen chopping board). This makes a much better bearing for the chrome plated adjuster bar.
Also in the header photo can be seen a new bracket to support the adjuster bar. This is a steel bracket faced with 10 mm thick polyethylene (a bit of kitchen chopping board). This makes a much better bearing for the chrome plated adjuster bar.
The bracket was bent from piece of 2.5 mm steel 40 mm wide. It was drilled with an 8 mm hole for attaching the bracket to the bandsaw base and also drilled out 24 mm on the other face of the bracket. The 10 mm polyethylene was drilled out 18 mm, the diameter of the adjuster bar, and attached to the bracket using 4 off M4 screws.
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The final mod was to replace the hook on the other end of the adjusted bar with one with a longer thread. I had many M8 x 150 mm coach bolts so I used one of these for the screw. The end of the adjuster bar was first drilled out 6.8 mm and the tapped M8 to accept the coach bolt.
It is always much easier to adjust the tension when the bandsaw arm is vertical because there is little tension in this position and the adjuster is easily turned.
The ability to adjust the spring tension and also the rate of descent using the hydraulic cylinder provides a myriad of possibilities to optimise the cutting for any material.
The ability to adjust the spring tension and also the rate of descent using the hydraulic cylinder provides a myriad of possibilities to optimise the cutting for any material.